From Alain de Botton’s novel, The Course of Love:

Love reaches a pitch at those moments when our beloved turns out to understand, more clearly than others have been able to, and perhaps even better than we do ourselves, the chaotic, embarrassing, and shameful parts of us. That someone else gets who we are and both sympathizes with us and forgives us for what they see underpins our whole capacity to trust and to give. Love is a dividend of gratitude for our lovers’ insight into our own confused and troubled psyche.

Rather than some notional idea or perfect complementarity, it is the capacity to tolerate dissimilarity that is the true marker of the right person. Compatibility is an achievement of love; it shouldn’t be its precondition.